Shelf



FIG. 1 is a top perspective view of a shelf showing my new design;

FIG. 2 is a bottom perspective view thereof;

FIG. 3 is a front elevation view thereof;

FIG. 4 is a rear elevation view thereof;

FIG. 5 is left side elevation view thereof;

FIG. 6 is a right side elevation view thereof;

FIG. 7 is a top plan view thereof; and,

FIG. 8 is bottom plan view thereof. 

The ornamental design for a shelf, as shown and described. 